Beijing — Chinese citizens dubious about their country’s legal system are seeking justice in an unusual place for the victim of an alleged attempted murder in China. They are taking the case to the White House.

More than 100,000 people have signed a petition on a White House website urging the US to deport the chief suspect in a 19-year-old unsolved case of poisoning that continues to excite strong emotions here. Adding piquancy to the case: The suspect is very well-connected politically in China.

In 1994, a chemistry student at one of China’s top universities, Tsinghua, called Zhu Ling was poisoned with Thallium, a chemical often used in rat poison. She did not die, but was left nearly blind, paralyzed, and brain-damaged, needing constant care from her increasingly aged parents.

Her fate has not been forgotten, says Wu Hongfei, a former journalist who has followed Ms. Zhu’s case closely, partly because she was pretty and smart and partly because Tsinghua is so prestigious. But the main reason, says Ms. Wu, is that the only real suspect in the case “had close ties to high ranking officials.”

Sun Wei, Zhu’s roommate at Tsinghua, was investigated by the police at the time of the incident, but was never charged, though reports at the time said she had access to Thallium. The police said there was not enough evidence to pursue the case; many ordinary citizens believe that evidence was covered up because Ms. Sun’s father's cousin had been deputy mayor of Beijing and her grandfather was reputedly a friend of then President Jiang Zemin.

“Because of her family background … she avoided punishment,” complained one netizen, posting as “@Jinse Guniang” on Sina Weibo, a Twitter-like social media platform.

Sun changed her name and is believed to now be living in the United States.

The case has erupted again into the public consciousness in the wake of last month’s arrest of a student for fatally poisoning his roommate at another prestigious university, Fudan, in Shanghai. The suspect in that case has confessed to putting poison in his dorm-mate’s water dispenser, saying he did it for a joke.

Zhu's case continues to rankle. On Monday, after just three days on the White House website, the petition concerning Sun had drawn more than the 100,000 signatures required for the US administration to offer a response. On Sina Weibo, terms relating to the case accounted for three of the top five search words.

Journalist Wu has little hope that the White House petition will do any good. Dissident artist Ai Weiwei “attracted a lot of international attention but he is still not allowed to leave China,” she points out. But as public pressure mounts at home, the authorities appear to be listening. Over the weekend, social media posts including such words as “Thallium” or “Zhu Ling” were being scrubbed from the Internet by Chinese censors, apparently afraid of criticism of the Chinese judicial system.

By Monday, the censors had lifted their search blocks. And even the state owned media have joined in the chorus of demands.

The online version of Peoples’ Daily, organ of the ruling Communist Party and Xinhua, the official news agency, shared a headline: “China, Ruled by Law, Should Seek Justice.” At long last, the victim of that unsolved poisoning seems to have friends in high places, too.